Aluminium die castings are assuming increasing importance in the automobile industry. The requirement to build lighter vehicles results in the expanded use of aluminium parts. Particularly where moved parts are concerned, it is advantageous to save weight, while at the same time having high stability. Components can be produced with small wall thicknesses by aluminium die casting.
Use of aluminium die casting for highly stressed components, however, also requires a set of production measures, some of which are already known. These are, in particular, blocking of displaceable tool parts and also sealing of displaceable tool parts with respect to one another, which are discussed in various versions in the prior art.
As illustrated in FIG. 1, die casting machines 1 for aluminium die casting, include essentially two main subassemblies: the mould-closing unit 2 and the casting unit 3. Further subassemblies are the ejection unit, the core-pulling device and the machine drive, including control.
The mould-closing unit 2 makes it possible to open and close the mould halves and lock them during casting, so that the closing force acts upon the mould. The most important components are a fixed chucking plate 4 for taking up the stationary mould half, a movable chucking plate 6 for receiving the movable mould half, machine columns 5 for guiding the movable chucking plate 6. The mould-closing unit is driven, in all die casting machines, by means of a hydraulic closing cylinder.
The casting unit 3 of a die casting machine has the task of conveying liquid metal into the die casting mould and of generating sufficient pressure upon the solidifying metal. The ejection unit 7 serves for removing the casting from the mould part and is installed in the movable chucking plate. The core-pulling device serves for the actuation of core cylinders on the die casting mould. They operate hydraulically and make it possible to introduce and release movable cores.
An important component of the die casting machine is the die casting mould, the inner space of which is identical to the contours and dimensions of the casting to be cast. Each die casting mould is made of at least two parts, so that the casting can be removed from the mould cavity after solidification.
Each die casting mould include a fixed and of at least one movable mould half. The fixed mould half is mounted on the fixed chucking plate of the die casting machine, while the movable moulding half is fastened to the movable chucking plate. The contact surfaces of the mould halves are designated as parting planes. Their position inside the mould is determined by the shape of the casting and the type of removal from the mould. The parting is designed such that a simple construction of the mould is made possible and the deburring of the casting is assisted. To avoid splashes of liquid metal, the mould parting plane has to be satisfactorily sealed off. In order to make it possible to fit the two mould halves together exactly, die casting moulds have to be provided with guides for the opening and closing movement. Movable cores are inserted for the purpose of forming bores, clearances, perforations, projecting surfaces, webs or ribs which do not run in the mould-closing direction.
DE 10 2007 017972 discloses a plastic injection-moulding die, the casing of which is supported geometrically against recesses. A type of blocking in this case takes place. This die, however, is not capable of managing the high pressures of aluminium die casting.
A solution to the problem of having to seal off the parting planes is found in DE 1963 9053, which discloses stepped contact points between die casting die parts. This embodiment, however, cannot fulfil the requirement as to the leak tightness and guidance of the die parts.